Copolymers of butadiene and tetrahydrofurfuryl methacrylate



Patented July 12, 1949 UNITED STATES TENT OFFICE COPOLYMERS OF BUTADIENE AND TETRA- HYDRGFURFURYL ME'KHACRYLATE Albert M. Clifford, Stow, (ihio, assignor to Wingfoot Corporation, Akron, Ohio, a corporation of Delaware Claims.

This invention relates to copolymers of tetrahydrofurfuryl methacrylate and butadiene-1,3 having rubber-like properties. More particularly, it relates to copolymers of these substances in such proportions and treated under such conditions as to result in plastic masses having the elasticity characteristic of natural rubber.

Various comonomers have heretofore been polymerized with butadiene- 1,3 to yield masses having widely varied properties. It has now been found that rubber-like masses which closely approach natural rubber in some of the more important properties of that material can be prepared by reacting the monomericsubstance, tetrahydrofurfuryl methacrylate, with butadiene- 1,3. However, in order to secure a material having the desired rubber-like properties, it is necessary that the monomers be reacted in certain proportions and that the polymerization take place in a certain manner. Specifically, the butadiene-1,3 should be present to the extent of 50-80% of the total monomers in the polymerizable mixture and these should be subjected to emulsion polymerization, as contrasted with mass polymerization or polymerization in solvents.

While the invention is more particularly characterized by the employment of tetrahydrofurfuryl methacrylate, having the formula rubber-like copolymers will not be obtained by interpolymerization of this with any and every comonomer. Thus, while butadiene-1,3 may be loosely termed a vinyl compound, it is more specifically a divinyl compound, and it is found that the characteristics of a divinyl compound such as a conjugated diene, particularly butadiene-1,3, and isoprene are those necessary to the production of a satisfactory rubber by copolymerization with tetrahydrofurfuryl methacrylate.

Also, the copolymerization, as mentioned, must be carried on in an aqueous emulsion, since mass polymerization and other methods of polymerization result in hard, inflexible materials, high polymers which may even be glass-like in their properties, or indefinite mixtures of polymers with great variation in properties and often characterized by lack of homogeneity. The polymerization is therefore performed in an aqueous medium which contains various ingredients to promote the reaction. These other constituents comprise a, catalyst or oxidant, such as sodium perborate or persulphate, an emulsifier, such as Aquarex D (sodium lauryl sulphate plus similar sulphates) and a buffer, such as a solution of disodium phosphate and citric acid (MacIlvaine buffers). Of course, these ingredients may be varied as desired and as described in the prior art in connection with emulsion polymerizations in general. The temperature during polymerization may vary from about 30 C. to about 30 C., or even higher, but is preferably maintained in the neighborhood of 35-50 C. The reaction will be continued for such period of time as will give yields of satisfactory magnitude and of the desired properties. Usually from several hours to a few days may be necessary, the time being controllable to a considerable extent by the addition of promoters, such as acetaldehyde and alkali metal cyanides. The rubber is produced in the form of a latex and this is coagulated by the addition of alcohol, common salt or other well.- lrnown coagulant.

To illustrate the practice of the invention, the following example is given, but it will be understood that the invention is not limited to the details thereof.

Example An aqueous emulsion was made up with the following composition:

5% solution of Aquarex D cc 10 MacIlvaine buffer (phosphate-citrate) cc 10 Sodium perborate grams 0.133 Carbon tetrachloride do 0.48 Butadiene-1,3 do 9.6 Tetrahydrofurfuryl methacrylate do 6.4

The ingredients were charged into four-ounce screw-capped bottles and agitated at a temperature of 50 C. for a period of about 116 hours. At the end of that time the resulting latices were coagulated with denatured ethyl alcohol and were washed and dried. The hydrogen ion concentration of the latex varied in accordance with the buffer which had been added, the disodium phosphate and the citric acid constituents of the bufier being proportioned so as to yield a latex which was, as nearly as possible, of the desired hydrogen ion concentration. It was observed that satisfactory yields of good rubbers were obtained when the hydrogen ion concentration was maintained within the range of about pH 6.5 to 7.3.

It will be noted that, in the foregoing example, the monomers were reacted in the proportions of parts of butadiene-1,3 to 40 parts of tetrahydrofurfuryl methacrylate. Similar results can be obtained when the monomers are reacted will be that: corresponding to the temperaturetot reaction, but gradually diminishing asthe gaseous butadiene compound is consumed in the. The aqueous emulsion will be agitatedconstantly during the polymerization-to insure. complete emulsification and contactfibe'twe'em'the two monomers and the water-soluble controlling.

DIOCESS.

agents of the polymerization.

The rubbers obtained by'the" practice ofth'e invention are soft and flexible and may be vulcanized into articles with theusualtvul'canihingt: ingredients for natural rubber, ortheymiay' include plasticizers, such as dibutyl sebacate, d tbutyl phthalate or tricres-yl phosphate. Where a plasticizer is employed, the rubbers are softer and'f'mtay beemployed where a-so'ft rubber is" required;

This application is a continuation in part :of

myiapplicatlon serial No. 452,161; men Jmyrz i;

- 1942, and nowabandoned;

Whiletherehas been described above'a pre ferred'embodiment of the invention; it will'be' understood that" variations may be" made therein Without departin from the spirit'ofth'e' invention orfiomt the scope of the appendedcla'imsl' I claim 1. A rubber-like aqueous emulsion c'opolym'er f"'50'80' parts of butadi'ene-LB and 50:20 partsoftetrahydrofurfuryl methacrylat'e:

2." A" rubber-like aqueous emulsion copolym'er" of'fiq parts'of 'butadiene-IB and 40'pa'rts oftetraze hydrofiirf'u'ryl" methacrylate.

A rubber-likemass whichisi the solids-off latex" from" an" aqueous emulsion copolymeriza= tion of 75 parts of butadiene-l,3 and 25 parts of tetrahydrofurfuryl methacrylate.

4. A method of producing a rubber-like prodnot which comprises heating an aqueous emulsion containing 50-80 parts butadiene-1,3, 50-20 parts. ofi tetrahydrofurfuml "'methaor'ylate and an effectiveamount of'a catalysficapable of polymeriZing the mixture at a temperature between 30 C. and 80 C. until the reaction is substantially complete; coagulating-:therresulting latex and recoveringagthe'zdesired product.

-5. A method of producing a rubber-like product-which: comprlses'copolymerizing an aqueous emulsion containingifio parts of butadiene-1,3, 40 parts of tetraliydfofurfuryl methacrylate, an effective:amountofi-sodium perborate as a catalyst, anzemulsifier an'dian amount of bufier to maintain the. emulsion at a pH within the range of 6.5 713? at a temperature of C. until the reaction is substantially complete, coagulating the result'lngrlatexc andirecovering the desired product? ALBERT Mi' CEIFF'GRD'."

REFERJENGES'I'IGITEB? The following referenlces; are. of .recordlinthe file of. this patent:.

UNITED STATESL,'

Number" Name j Date 21291666 Barrett et al. Sept; 131.1938'i 2;218136'2" starkweather O'ctgl'ii; 1940 2,282,515 Arnold et al.' FebZ 18; I941 2279293 O1ifiord." -A'pr; 14',1'94;2'"

FOREIGN BATEN'IS' Number Country) mate 8801822 GreatBritain' dctf3li;f 1931' 

